The planet Thoron was located 12,000 kilometers from Krypton above and far of Rao sun (similar the size of Mars) in the story of Earth 2 by DC comics (The Daxam parallel). The Thoronians lived in great cities pyramid of the planet, the quality of life of the planet as water and vegetables, they have similarities with the Kryptonians, as also have kinship with Krypton be descendant they, but other their ancestors came from another dimension to colonize the planet, unifyin two species humanoid as thoronian. Thoron was an isolated planet within the Rao system, but the shock wave originated Of the destruction of the planet Krypton, almost destroyed Thoron, leaving few survivors to rebuilding a new life on the planet in its ruins.
But Halk Kar was the prince of planet Thoron, who escaped at the time of destruction, the ship is hit by the kryptonite meteorites on takeoff, getting in suspense animation for years, until falling into the earth, Halk Kar meets with Kal-L (superman of earth 2), without memory, adopting a profile of brother of the superman, Halk Kar and Superman joined forces to stop a criminal named "Wrecker" Ross, but during the incident, Halk Kar suffered an electric shock which restored his memory, returning later to its origin planet to escape the deadly radiation of the "lead" of the earth.
In the TV series Supergirl, the character Mon-EL has the same story as Halk kar.